81900051 has 16 divisors (see below), whose sum is σ = 115785600. Its totient is φ = 51349248.

The previous prime is 81900023. The next prime is 81900059. The reversal of 81900051 is 15000918.

It is not a de Polignac number, because 81900051 - 2⁹ = 81899539 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81899994 and 81900030.

It is not an unprimeable number, because it can be changed into a prime (81900059) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2755 + ... + 13091.

It is an arithmetic number, because the mean of its divisors is an integer number (7236600).

Almost surely, 2^81900051 is an apocalyptic number.

81900051 is a deficient number, since it is larger than the sum of its proper divisors (33885549).

81900051 is a wasteful number, since it uses less digits than its factorization.

81900051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10498.

The product of its (nonzero) digits is 360, while the sum is 24.

The square root of 81900051 is about 9049.8646951211. The cubic root of 81900051 is about 434.2715619409.

Adding to 81900051 its reverse (15000918), we get a palindrome (96900969).

The spelling of 81900051 in words is "eighty-one million, nine hundred thousand, fifty-one".